Reciprocating slat-type conveyors are well known in the art. This type of conveyor system provides a convenient method of discharging refuse (or other loads) rearwardly from a trailer without tilting the trailer. The system typically includes a plurality of slats, independently driven with three or more drive means in a forward and rearward direction such that at any given moment either all slats or every third slat is in movement. Thus, a relatively short reciprocating movement will displace over time the entire load out of the trailer in a stepwise movement. Examples of such conveyors are disclosed in U.S. Pat. No. 4,143,760 (Hallstrom), U.S. Pat. No. 4,184,587 (Hallstrom), U.S. Pat. No. 4,691,819 (Hallstrom), U.S. Pat. No. 4,709,805 (Foster) and U.S. Pat. No. 5,934,445 (Foster et al.).
When the loads transported on a trailer or by a vehicle contain a liquid component, liquid may seep onto conveyor slats, between conveyor slats onto the drive means and out of the trailer or vehicle onto the road. This is especially problematic when the load is refuse such that the liquid may be toxic and its escape from the trailer or vehicle contravenes environmental regulations. Various improvements have been disclosed in response to the seepage of toxic liquids from the load. U.S. Pat. No. 6,013,585 (Foster et al.) describes a method for manufacturing conveyor slats that are chemical resistant and non-corrosive. Each of U.S. Pat. No. 5,165,525 (Quaeck), U.S. Pat. No. 5,267,641 (Hallstrom, Jr.) and U.S. Pat. No. 5,547,067 (Foster) disclose base members to which the conveyor slats are attached. The base members may be attached, configured or sealed in such a manner so as to prevent the leakage of liquid beneath them. U.S. Pat. Nos. 5,088,595 and RE35,156 each disclose a liquid receptacle that collects liquid. The liquid receptacle extends beneath a portion of each base member.
Reciprocating conveyors may be attached to frameless trailers, as described in U.S. Pat. No. 5,957,267 (Quaeck et al.). Frameless trailers minimize the total mass of the load by eliminating components of the conventional framework assembly that normally supports the load. One drawback associated with the use of a frameless trailer is the damage sustained by the piston rods, which are components of the drive means, when loads are dropped on the conveyor slats above the piston rods. U.S. Pat. No. 5,957,267 adds fixtures to the drive means assembly, which fixtures bear the loads that are dropped upon the conveyor slats.
A further limitation that has been identified in prior art reciprocating conveyors is the position of the drive means. When such reciprocating conveyors are not fitted with base members, liquid waste seeps onto the drive means located beneath the conveyor slats, thus hampering movement of the conveyor slats. In liquid impermeable conveyor systems, it is expensive and labour intensive to mount a drive means below the conveyor slats. This is because an extensive hose and tubing system is necessary to connect the hydraulic fluid supply that is frequently a component of such drive means to drive units such as pistons. Thus U.S. Pat. No. 5,222,590 (Quaeck) discloses a configuration in which the drive means is positioned outside of the container in which the load is transported.
There are a number of limitations associated with prior art reciprocating conveyors, including improved reciprocating conveyors adapted to transport loads having a liquid component. Adding seals to each base member increases the costs of manufacture. Using base members to prevent the leakage of liquid beneath them is undesirable because such base members are susceptible to damage from the impact that they sustain when loads are dropped upon them. Replacing such base members is more costly and time-consuming when they are sealed. Furthermore, changing the configuration of the slats when they have a complicated base member structure, whether or not such structure includes seals, is also costly and time-consuming. Moreover, such seals trap moisture amongst the base member structure, thus making it susceptible to damage from the freezing of such moisture in cold temperatures. Finally, previous means for preventing leakage through the conveyor could not be attached to the conveyors of more than one manufacturer, since the width of the conveyor slats varies depending on who manufactures them.
There are other drawbacks to the prior art liquid collection receptacles. The receptacle is small and must be emptied periodically, since failure to empty the receptacle will result in the drive means for the conveyor becoming submerged in liquid waste. Furthermore, the dual trays and centre trough orientation of the liquid receptacle necessitates the welding of the components of the receptacle such that each weld must be covered with sealant to prevent leakage, thus adding to the cost of manufacturing the receptacle. Moreover, the prior art receptacle is fastened to cross members by rivets or bolts. Each fastening means must be individually sealed. When a reciprocating conveyor is used with the prior art receptacle, debris accumulates between the conveyor slats and pan, which necessitates frequent cleaning and repair.
There is disclosed herein a refuse collection system with a reciprocating conveyor for use with a transport vehicle, this system having little or no leakage of liquid waste.
Accordingly, one aspect of the invention herein comprises a refuse collection system for use in combination with a transport vehicle. The system includes a refuse container for the vehicle, this container having a length and including two lengthwise extending sidewalls, a front wall, a rear door and a bottom. The bottom includes a frame having at least two cross members and at least two slat-bearing bars extending across and mounted on the cross members. A platform is attached to and mounted on the frame and has at least two elongated slats, each engaged with one of the at least two slat-bearing bars. The at least two elongated slats are spaced apart from one another so as to permit liquid refuse to seep between and through the slats. A drive means is attached to the at least two elongated slats and situated distal from the platform out of the path of the liquid refuse. The drive means moves the slats between a first and a second position in a lengthwise direction relative to the slats. The system also has an elongate tray extending in a lengthwise direction relative to the container, attached to the frame, and situated beneath the platform and the at least two slat bearing bars so as to catch the liquid refuse that seeps between and through the at least two slats.
According to another aspect of the invention, a transport trailer comprises a trailer unit for a transport vehicle, this trailer unit including a transport container having a length and including two lengthwise-extending sidewalls, a front wall, a rear door and a bottom. The bottom is formed by a frame constructed of cross-members and slat-mounting bars extending across and mounted on the cross-members. A plurality of elongate slats extend lengthwise in the trailer unit and are mounted on the slat mounting bars for lengthwise reciprocation. Adjacent slats are spaced-apart from one another so as to permit liquid to seep between and through the slats and the slat-mounting bars. A drive mechanism is attached to the slats for reciprocating them between first and second positions, this drive mechanism being mounted on the trailer unit. An elongate tray extends in a lengthwise direction relative to the container, is attached to the frame, and is situated beneath the slats and the frame. This tray is adapted to catch the liquid that seeps between and through the slats and the slat-mounting bars.
According to a further aspect of the invention, a transport vehicle comprises a wheeled vehicle unit including a transport container having a length, two lengthwise-extending sidewalls, a front wall, a rear door, and a bottom. The bottom is constructed with transversely extending frame members and is adapted to support a reciprocating slat-type conveyor mounted on top of the frame members during use of the vehicle. An elongate tray extends in a lengthwise direction relative to the container, is attached to the bottom beneath the frame members, and is adapted to catch liquid from the contents of the container that can seep through the conveyor and between the frame members during use of the vehicle with the slat-type conveyor. The tray extends beneath most of the length of the transport container.
Directional references herein such as “vertical” and “horizontal” are for convenience of description only. It will be appreciated by one skilled in the art that (a) the invention may be tilted, and (b) even when placed on the level, a moderate departure from the horizontal, vertical etc. is permissible. Further, terms such as “wall” are intended to have a broad meaning to include a member in any orientation which serves the function of such member.